A computer at the Connecticut home where Newtown, Conn., school shooter Adam Lanza lived with his mother was badly damaged, perhaps smashed with a hammer, said police who hope the machine might still yield clues to the gunman's motive.

The computer's hard drive appeared to have been badly damaged with a hammer or screw driver, law enforcement authorities told ABC News, complicating efforts to exploit it for evidence.

Officials have "seized significant evidence at [Lanza's] residence," said Connecticut State Police spokesman Paul Vance, adding that the process of sifting through that much forensic evidence would be a lengthy and "painstaking process."

Authorities also told ABC News that the weapons used in Friday's rampage at Sandyhook Elementary School, which left dead 20 children and seven adults including Lanza's mother Nancy, were purchased by his mother between 2010 and 2012.

According to the Bureau of Alcohol Tobacco and Firearms, Lanza visited shooting ranges several times in recent years, and went at least one time with his mother.

The first funeral for a child killed in the massacre was held today in Fairfield, Conn., where mourners gathered to remember the too-short life of first-grader Noah Pozner.

Authorities also revealed this morning that two adult women shot during the rampage survived and their accounts will likely be integral to the investigation.

"Investigators will, in fact, speak with them when it's medically appropriate and they will shed a great deal of light on the facts and circumstances of this tragic investigation," Connecticut State Police Lt. Paul Vance said at a news conference today.

Both survivors are women and are now home from the hospital after being shot, police said. Officials had previously mentioned just one adult survivor. The women have not been identified and police did not give details on their injuries.

Police say Adam Lanza, 20, forced his way into Sandy Hook Elementary School on Friday, spraying bullets on students and faculty. Lanza killed 20 children and six adults before turning the gun on himself.

Lanza also killed his mother Nancy Lanza at the home they shared before going to school.

"There are many, many witnesses that need to be interviewed," Vance said. "We will not stop until we have interviewed every last one of them."

Vance said the investigation could take weeks or months to complete. "It's not something done in 60 minutes like you see on T.V."

Some of the other key witnesses will be children who survived the shooting spree by playing dead, hiding in closets and bathrooms and being rescued by dedicated teachers.

"Any interviews with any children will be done with professionals...as appropriate," Vance said. "We'll handle that extremely delicately when the time arises."

Officials said today that the Sandy Hook Elementary School, where the shooting took place, will be closed "indefinitely."

Both the school and the home where shootings took place are being held by police as crime scenes and Vance predicted authorities would spend "months" investigating the elementary school.

All Newtown schools are closed today to give residents more time to cope. Every school except for Sandy Hook is expected to re-open Tuesday.

The town of Monroe has offered to open to Sandy Hook students the Chalk Hill School, a former middle school that currently houses the town's EMS and recreational departments.

Officials in Monroe, less than 10 miles from Newtown, say the building could be ready for students by the end of the week, but have not yet set a date to resume classes.

Nearly 100 volunteers are working to ensure the building complies with fire and security regulations and are working to retorfit the school with bathroom facilities for young children.

"We're working to make the school safe and secure for students," said Monroe Police Department spokesman Lt. Brian H. McCauley.

The neighboring community's school is expected to be ready to accommodate students in the next few days, though an exact schedule has not yet been published.

While the families grieve, federal and state authorities are working around the clock to answer the question on so many minds: "Why?"

ABC News has learned that investigators have seized computers belonging to Adam Lanza from the home he shared with his mother. Three weapons were found at the school scene and a fourth was recovered from Lanza's car. Lanza had hundreds of rounds and used multiple high-capacity magazines when he went on the rampage, according to Connecticut State Police.

Vance said that every single electronic device, weapon and round will be thoroughly examined and investigated as well as every aspect of Lanza's life going "back to the date of birth."

ABC News has learned that both the shooter and his mother spent time at an area gun range; however it was not yet known whether they had shot there.

President Obama delivered an emotional address at an interfaith prayer vigil in Newtown on Sunday night, comforting the community.

"I come to offer the love and prayers of a nation," the president said. "I am very mindful that mere words cannot match the depths of your sorrow nor can they heal your wounded hearts. I can only hope it helps to know you are not alone ... and that all across this land we have wept with you."

"These tragedies must end," Obama said. "And to end them we must change."

Thousands came out of the prayer vigil where Red Cross members distributed stuffed dogs to children and adults wept in the auditorium.

"We needed this. We needed to be together, here in this room, in the gymnasium, outside the doors of this school, in living rooms around the world," said Rev. Matt Crebbin, senior minister of the Newtown Congregational Church. "These darkest days of our community shall not be the final word heard from us."